GitHub MCP Server

github_compare_commits

Compare any two commits, branches, or tags to see exactly what changed. Provide base and head references to retrieve a paginated list of differences.

Instructions

Compare two commits, branches, or tags to see what changed between them

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "owner": "<owner>",
      "repo": "<repo>",
      "base": "<base>",
      "head": "<head>"
    },
    "name": "github_compare_commits"
  }
}

Input Schema

Name	Required	Description
`base`	Yes	Base ref (branch, tag, or SHA)
`head`	Yes	Head ref (branch, tag, or SHA)
`page`	No	Page number
`repo`	Yes	Repository name
`owner`	Yes	Repository owner (organization or username)
`per_page`	No	Results per page (max 100)

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Sep 6, 2026

TDQS

B3.2/5.0

Behavior2/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations are provided, so the description carries the full burden of behavioral disclosure. It only states the basic comparison operation and says nothing about the response shape (commit list vs. file diffs vs. stats), pagination behavior, or access requirements. 'What changed' is left ambiguous, which is a significant gap for a diff-oriented tool.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

A single 13-word sentence with the verb front-loaded and zero filler. Every word earns its place, and the scope of what is compared (commits, branches, tags) is stated immediately.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness2/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no annotations and no output schema, the description should disclose what the response contains — the entire purpose of a compare call is the diff representation — and it does not. Parameter coverage is complete, so the tool is callable, but an agent cannot anticipate whether results come back as a commit list, file patches, statistics, or some combination, nor how pagination affects the result.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so all six parameters are already documented in the schema, including base/head as 'ref (branch, tag, or SHA)'. The tool description's mention that base/head can be commits, branches, or tags slightly reinforces the schema but adds little new meaning. Baseline 3 is appropriate since the schema does the heavy lifting.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description uses a specific verb ('Compare') with concrete resources (commits, branches, tags) and an outcome ('see what changed between them'). The verb differentiates it from the sibling list/get tools, though no sibling is named explicitly, so it stops short of maximal distinction. Clear and unambiguous overall.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Usage is implied: use this when you want to diff two refs. However, there is no explicit when-to-use, when-not-to-use, or mention of alternatives such as github_list_commits or github_get_commit, which an agent might confuse with this tool when trying to inspect changes between refs.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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